Various fluid pumping systems powered by internal combustion engines have been developed. Examples of such systems are shown in U.S. Pat. Nos. 3,606,591; 3,260,213; 3,995,974; 4,093,405; 4,097,198; and 4,205,638. U.S. Pat. No. 4,459,084 discloses a power system in which a cam driven by a steam piston in turn drives a pair of opposing fluid pistons. The pressurized fluid is stored in a high pressure accumulator and directed through a hydraulic motor when desired into a low pressure accumulator. U.S. Pat. No. 2,334,688 discloses an internal combustion engine in which the output is governed by the length of the stroke of the piston.
U.S. Pat. Nos. 3,751,905; 4,093,405; and 4,115,037; and Ferris, "Toward a Hydraulic Prime Mover," Paper No. 780748, Soc. of Auto. Engineers 1978; show opposed combustion piston arrangements in fluid pumping systems.
Other patents in this field are listed on the patents mentioned above in the cross reference to related applications.